Well, that's rather practical and if it helps then its a great idea. Archive: https://archive.today/RLgXM From the post: >>My rental agreement meant I couldn’t drill holes in walls. The only way for air to get in or out was the 18mm gap under my door. This led to my main idea: if I could actively push stale air out from under the door, the negative pressure in the room would pull fresh air in through the trickle vent.